Amputation of the foot is one of the most serious problems in the care of diabetics both in terms of the cost to the patient and in terms of the cost to the health care system. Foot infection accounts for 20% of hospital admissions in diabetic patients. There were approximately 86,000 amputations related to diabetes in 1999. The annual treatment cost of amputees within this group was estimated at $1.2 billion by the Center for Disease Control in 1997. This number is going to escalate because the overall prevalence of diabetes, now involving 16 million Americans, is approaching epidemic scale. The emphasis is on early intervention and prevention that in turn, depends on early detection and understanding the development of foot infections. The progression of diabetes to infection and amputation is difficult to follow because there are many factors contributing to infection. However, neuropathy generally leads to ulcers and infection. Our hypothesis is that changes in the intrinsic mechanical properties of the foot contribute to the alterations that lead to callus formation and ulceration. We will develop methods to image the intrinsic mechanical properties of the soft tissues of the foot in vivo. Current methods can not separate the intrinsic properties from the shape and structure and the intrinsic properties are more directly tied to the progression of a metabolic disease like diabetes. The intrinsic mechanical properties we will map throughout the plantar soft tissues include the: shear modulus, Poisson's ratio, and damping coefficient. There are several potential benefits to clinical medicine: early characterization of diabetic damage leading to ulceration and quantitative characterization of atrophic fat pads. The potential benefits to basic science include characterization of normal and abnormal fat pads for numerical models of the foot during ambulation and understanding the mechanisms through which diabetes degrades the plantar fat pads and other soft tissues.